Transmitting data from a calling party towards a called party via a communications network is based on the use of nodes which are adapted to enable the transmission of data from the calling party towards the called party. The data to be transmitted from the calling party to the called party is exchanged in a user plane of a transmission path, wherein nodes are arranged in the user plane via which the data is exchangeable. The transmitted data is usually encoded by a particular codec. In a control plane of the transmission path, further nodes may be arranged which are adapted to control the data transmission in the user plane.
Conventionally, the communications network architecture comprises a Radio Access Network (RAN) adapted for communicating data of a mobile communication entity such as a mobile phone or a laptop and a Core Network (CN) adapted for communicating data towards another or the same Radio Access Network or towards a public switched telephone network (PSTN).
In the following, transmitting voice data via the Radio Access Network will be described.
The network architecture of the Radio Access Network comprises a base station controller (BSC) in the case of GSM Radio Access (GERAN/GRAN) and a radio network controller (RNC) in the case of Universal Terrestrial Radio Access Network (UTRAN), respectively, both being adapted to communicate with nodes of a Core Network, such as call control nodes and Media Gateways (MGw). Media Gateway nodes typically are controlled by one or more call control nodes such as Mobile Switching Centre (MSC)/Mobile Switching Centre Servers (MSC-S).
A user plane of the transmission path comprises the Base Station Controllers and/or the Radio Network Controllers, and the media gateway nodes. A control plane of the transmission path comprises the Base Station Controllers and/or the Radio Network Controllers, and the call control node(s).
If a BSC or a RNC node is connected to a plurality of call control nodes, allowing for load balancing and redundancy, this is often referred to as MSC in pool (MiP).
Transmitting voice data from a calling party towards a called party via at least one media gateway node requires setting up the transmission of the voice data. In particular, a coding of the voice data to be transmitted may be performed in the user plane of the transmission path using at least one codec. In particular, coding operations of the voice data within the user plane are based on Out of Band Transcoder Control (OoBTC) procedures which allows for negotiating the codec types or codec modes on a call-by-call basis using out of band signaling such that a proper speech quality and/or an efficient use of bandwidth may be achieved.
In the context of this application, the term “set up a transmission of voice data” may particularly denote any initialization or starting of a data transmission, wherein parameters or characteristics for the data transmission may be defined. In particular, a calling party, a called party and/or a data transmission path may be determined. In particular, a set up of the data transmission may be negotiated in a control plane of the transmission path.
The term “calling party” may particularly denote any communication partner device which may be adapted to initiate or start a voice transmission from one connection point to another connection point. In particular, a calling party may be a source of the voice data (such as a user equipment) to be transmitted towards at least one communication partner device or may be any communication partner device (such as a base station controller) arranged downstream of the voice data source in a transmission path.
The term “called party” may particularly denote any communication partner device which may be adapted to terminate or to be a termination of a voice data transmission path from one connection point to another connection point. In particular, a called party may be a destination of the voice data (such as a user equipment) to be transmitted or may be any communication partner device (such as a base station controller) arranged in a transmission path upstream of the voice data destination.
The term “user plane” may particularly denote a plane or level in a data transmission path in which payload data such as voice data is transmitted.
The term “control plane” may particularly denote a plane or level in a data transmission path in which controlling of the data transmission, particularly of the user plane data transmission path, may be performed. Within the “control plane” signaling traffic pertaining to a (intended) user plane traffic is handled. Therefore “control plane” is often also referred as “signaling plane”.
The term “node” may particularly denote a communication partner device which may be configured for communication with one or more other nodes or communication partner devices in a network architecture. In particular, a node may be part of a user plane or a control plane of a data transmission path.
The term “call control node” may particularly denote any kind of node adapted to control at least part of a user plane transmission path from a calling party towards a called party. In particular, a call control node may be adapted to communicate with at least one of a calling party, a called party, and at least one media gateway node.
The term “media gateway node” may particularly denote any node via which voice data is transmittable. A media gateway node may comprise an access or incoming termination and an outgoing termination, wherein the incoming termination and the outgoing termination may be adapted to receive voice data according to a particular codec and to send transmitted voice data encoded by a particular codec, respectively.
The term “codec” may particularly denote a coding format or a coding scheme usable for encoding voice data to be transmitted. In particular, when changing a particular codec of the data to a further codec of the data, transcoding operations may be applied to the data.
Referring to FIG. 10, an example of a Network comprising a Media Switching Center in Pool (MIP) is illustrated. The Network comprises three Base Station Controllers BSC1, BSC2, BSC3, each of which being adapted to communicate with a different one of three media gateway nodes MGW-1, MGW-2, MGW-3, respectively. Each of the media gateway nodes MGW-1, MGW-2, MGW-3 can be controlled by any of three call control nodes MSC-S1, MSC-S2, MSC-S3 being adapted as Mobile Switching Center Servers. The media gateway nodes MGW-1, MGW-2, MGW-3 and the call control nodes MSC-S1, MSC-S2, MSC-S3 form a Core Network (CN).
According to the network architecture, each call control node MSC-S1, MSC-S2, MSC-S3 is adapted to serve traffic, particularly is adapted to control a transmission of voice data, via each one of the media gateway nodes MGW-1, MGW-2, MGW-3. Therefore, a failure of a call control node MSC-S1, MSC-S2, MSC-S3 or a media gateway node MGW-1, MGW-2, MGW-3 may be compensated in that a further call control node MSC-S1, MSC-S2, MSC-S3 can be used for controlling the transmission of the voice data or a further media gateway node MGW-1, MGW-2, MGW-3 can be used for transmitting the voice data, respectively. Further, load balancing may be achieved for multiple transmissions of voice data, since various media gateway nodes MGW-1, MGW-2, MGW-3 may be used for transmitting voice data.
In particular, a transmission of voice data from the Base Station Controller BSC1 to the Base Station Controller BSC2 via the media gateway nodes MGW-1 and MGW-2 will be described in the following in more detail.
Referring to FIG. 11, setting up the transmission of the voice data for a call is illustrated. The transmission of voice data from the originating Base Station Controller BSC1 to the terminating Base Station Controller BSC2 via the two media gateway nodes MGW-1, MGW-2 is controlled by the two call control nodes MSC-S1, MSC-S2. The call control node MSC-S1 is adapted to control at least the media gateway node MGW-1, and the call control node MSC-S2 is adapted to control at least the media gateway node MGW-2.
Both the originating Base Station Controller BSC1 and the terminating Base Station Controller BSC2 are adapted to use Pulse Code Modulation (PCM) as codec when communicating or exchanging the voice data via the media gateway nodes MGW-1, MGW-2. The transmission of the voice data within the media gateway nodes MGW-1, MGW-2 is based on signal transcoding from PCM to compressed speech (CS) and signal transcoding from CS to PCM. In particular, a first termination T1 of the media gateway node MGW-1 is seized to PCM as the type for the incoming voice data. A second termination T2 of the media gateway node MGW-1 representing an outgoing termination of the media gateway node MGW-1 is adapted to operate on the codec type CS, as a first termination T3 of the media gateway node MGW-2 does. A second termination T4 of the media gateway node MGW-2 representing an outgoing termination is adapted to send the transmitted voice data towards the base station controller BSC2 using the PCM.
The termination T1 and the termination T2 are part of a so called context C1, while the termination T3 and the termination T4 are part of another context C2. In the context of this application, the term “termination” may particularly denote a source or sink of one or more media streams, such as voice. In the examples shown, the terminations T1 and T3 are sinks for the direction of a voice stream towards BSC2, while the terminations T2 and T4 are sources for the direction of a voice stream towards BSC2. In the opposite voice stream direction of the examples shown, the terminations T1 and T3 are sources for the direction of a voice stream towards BSC1, while the terminations T2 and T4 are sinks for the direction of a voice stream towards BSC1.
The term “context” may particularly denote an association between a collection of terminations. In the examples shown, the context C1 is an association of the terminations T1 and T2, while the context C2 is an association of the termination T3 and T4. Although only 2 termination contexts are shown, further contexts comprising two or more terminations may be present in the user plane.
In this example, the coding operations of the voice data within the media gateway nodes MGW-1, MGW-2 are based on Out of Band Transcoder Control procedures. In particular, the coding operations C1 and C2 used within the media gateway nodes MGW-1, MGW-2 are defined by OoBTC used for negotiating a selected codec.
Transmission of encoded speech between the contexts C1 and C2 is wanted to increase bandwidth efficiency within the Core Network, and the negotiation via OoBTC is adapted to reach this goal. This approach accepts that, when using the network configuration as described above, the speech quality of the transmitted voice data may be somewhat deteriorated, and a system resource usage of the media gateway nodes MGW-1, MGW-2 may be significantly increased due to the encoding and decoding operations within the contexts C1, C2.
Referring to FIG. 12, a further set up of a transmission of voice data from the Base Station Controller BSC1 towards the Base Station Controller BSC2 is illustrated.
The network configuration during this set up of the data transmission is similar to the network configuration illustrated in FIG. 11. However, the user plane comprises only one media gateway node MGW-1 via which the voice data is transmittable. The call control node MSC-S1 is adapted to control an originating side of the media gateway node MGW-1, and the call control node MSC-S2 is adapted to control a terminating side of the media gateway node MGW-2.
Similarly to FIG. 11, the originating Base Station Controller BSC1 is adapted to use PCM as type for encoding the voice data transmitted towards a first termination T1 of the media gateway node MGW-1. The terminating Base Station Controller BSC2 is adapted to operate on PCM as type which is also used by the fourth termination T4 of the media gateway node MGW-1. The originating call control node MSC-S1 and the terminating call control node MSC-S2 are adapted to enforce a selected codec, particularly compressed speech CS, on the second termination T2 and the third termination T3 of the media gateway node MGW-1, respectively. Thus, transcoding operations C1, C2 are existent within the media gateway node MGW-1 when transmitting the voice data.
However, setting up the transmission of voice data as illustrated in FIG. 12 may also result in an unnecessary consumption of processing capacity of the media gateway node MGW-1 as well as in a degradation of the speech quality of the transmitted voice data. Because both contexts C1 and C2 are now located within the same media gateway node MGW-1,no network bandwidth saving can be achieved, since PCM to PCM is used within the media gateway node MGW-1 for the access and termination codecs and an encoding towards CS and decoding back to PCM may deteriorate speech quality and will add up processing load.